Bellows-type expansion compensator with spring-controlled tubular braided shroud



3,044,805 -CONTROLLED 2 Sheets-Sheet l L .M n mo E ND N Ec n WM o I. YT A K A A. MCDONALD ON COMPENSATOR WITH SPRING TUBULAR BRAIDED SHROUD BELLOWS-TYPE EXPANSI h. D OM @N D Z M 0 m. X

July 17, 1962 Filed June 22, 1959 F. A. MCDONALD 3,044,805 -TYPE EXPANSION CoMPENsAToR WITH SPRING-CONTROLLED July 17, 1962 BELLows TUBULAR BRAIDED SHROUD 2 Sheets-Shes?l 2 Filed June 22. 1959 MN mm um l O Nm @N .VN N

INVENTOR. FRANK /\.MCDONAL.D

BY MMM/1 A-r 'ronNEvs 3,044,805 .Patented July 17, 1962 3 044 S05 AELLUWS-TYPE EXBANSIN COMFENSATIR WITH Y SPRING CNTROLLED TUBULAR BRAIDED SHRUD FrankfA. McDonald, 63 St., San Francisco, Caliif.

Filed .lune 22, i959, Ser. No. 822,901 6 Claims. (Cl. 285-45) compensator includes a tubular metallic bellow/vs, the opl posite ends of which are secured to pipe sections. The bellows are-made of relatively thin metal which may rupture when subjected to relatively high pressures and ilexing, unless the bellows lare otherwise protected and supported.

Asthe cardinal object of my invention, it is proposed to provide a spring-controlled tubular braid shroud which is arranged in surrounding relation with the bellows. The shroud is maintained under tension by the springs. The

tension placed on the shroud prevents the bellows from bulging to one side or the other, when the bellows is compressed, and the shroud provides an exterior support for the bellows. The spring control keeps tension on the braided shroud throughout the cycling period, which might involve axial movement as well as lateral or angular movement.

Another object of lthe invention is to ,provide a braided shroud for` the bellows that will substantially relieve the bellows from torque; and, at the same time, the shroud will not prevent the bellows from flexing.

Other objects and advantages Will appear as the specication continues. The novel features of the invention will be set forth in the, appended claims.

Drawings For a better understanding of the invention, reference should be hadfto the accompanying drawings, forming part of this spceiiication, in which:

FGURE l is a sideelevational view of my bellowstype expansion compensator with spring-controlled tubular braided shroud;

V`FIGURES2-and 3 are transverse sectional Views taken ralong-the planes H--Il and III-'HL respectively, of FIG- `URE l;

FIGURE 4 is a longitudinal `sectional View taken through the assembled. expansion compensator; and

FIGUR-E5 isian elevational View ofthe tubular braided i shroud,- partly shown insection.

While Ivhavev shown only theepreferred form -of my inventionritshould be understood that various changes,

.ormodifications, may .be made within the vscope of the annexed .claimswithout departing `from the spirit thereof.

Detailed Description sections into a fluidecarryingcconduit lline C (seeFlGURE i .1). A-For, this purpose, I have disclosed thepipe ysections A and B as l'being formed with end flanges id andll,

respectively. These' anges'may be secured .by'boltsj12 to companion flanges Altaand llaythe latter'beingjprovided yon the confronting ends of pipes'i and 14"com prising part of the conduit line C.

it will be appreciated, `of course, that theconduitline fC 4may be used for steam, condensateandhot Water/heating systems .or other purposes. The pipesti'andtljiwill Vbe caused to expand and contract ldue, to changes in temperature/s of'fluidspassing therethrough; and, also, due to ylluctuations in' temperatures of thel ambient'air.

An anchor 15 may be xed to--the pipe section A so that the latter constitutes a Fixed End, as suggested bythe legend inFlGURE l. `The pipesectionB is disposed at the Floating End of the compensatonas indicated in the same View by the legend.

Intermediate angesiD, and E are xedto the inner ends of the pipe sections A and B, respectively, as illustrated in FIGURE 4. It will be seen that a tubular metallic bellows E has lits opposite ends le and' 17 abuttingthe anges Dand E and ,being secured thereto -by any suitable means, suchas by welding or .brazing 'Thus it will be apparent thattheconvolutions 18 of the bellows'F `will be compressed, when the` pipe sections A and'B are moved toward one another in` an axial directon,-wh1e the convolutions will be expanded, as these ypipepsections are moved away from one another.

The tubular metallic bellows F Vdeiines a passageway `19 which communicates ywith the bores-2t)` and 21 of' thepipe sections A and B, respectively (see FIGURE 4). This passageway is adapted to convey' fluid through the com pensator, the temperatures and pressures of Awhich'will vary considerably. Forthe purpose of supporting'the bellows and preventing thelatter from'rupturing during expansion and contraction, a springecontrolled tubular braided shroud G has been telescoped over` the bellows.

It will be apparent that inner and outer-circular bands 22 and 23, respectively, are secured tothe right-hand 0r Floating End of the shroud'G, andthat thesebands are welded Aat't to the intermediate'ange E. Moreover, inner and outer circular bands 2,5 and 26 are 'secured to the left-hand end of the shroudl G. A plurality of bolts Z7 are welded or otherwise Alixed to' the outer band26, and these bolts slide freely through 'openings-2S fashioned in the intermediatejange D. Nuts-29 are adjustably threaded on the outer ends ofthe bolts *2.7,4 and compression springs 3?. are interposed between' thenuts 29 and the :Flange D.

With particular reference to FIGURES 1 and 4 pipe section A may be regarded as being fixed, and the pipe section Bas being movable. "l`he'right-hand endof -the 'tubular 'braided shroud G is anchored to` the kvpipe-section-B, while the .lefthand end of this shroud is movable toward and away `from the intermediate `ange D, asthe 'bellows is contracted and expanded, respectively. v

Particular attention iscalled tothe vfact that'the tension placed on the shroud 'G will prevent the bellows'F from bulging to one side or therother of the centerline 310i the bellows when the latter is compressed. LNormally, braid will belly out in considerable proportions when the ends of the: tubularshroud are compressed'toward one another; therefore, it 'would lose its'ipressure holding strength or support for'the bellows Rif the springs 30 were not provided. Therefore, there' is afdis-` tinct need for the spring control whichftke'epstension on the `braided shroud G throughout the cycling period.

This period might ,involve axial movement las vWellfas lateral or angular movement 'ofthe'bellows lt will be noted that theshroud'G4 istfrusto-coni'call'or bell-shaped, the larger end 32 vof vthe cone'being"xedto the circular bands 25 and 26, While the smaller'-^endf=33 ofthe cone. tis ixed tothe ,circular bands 22 andfZS. This conical arrangement permits lthe braided shroud rG act/tasse 3 to move fast and freely under tension of the springs 30 at the Fixed End, that is, adjacent to the fixed pipe section A. The bellows F does not move at its left-hand portion in FIGURE 4 to the degree that it does at the right-hand or Floating End.

As clearly illustrated in FIGURES 3 and 4, the smaller end 33 of the shroud G contacts with the bellows F. On the other hand, FIGURES 2 and 4 disclose that the shroud G is spaced from the bellows F at the larger end 32 of the shroud. The purpose of the conical shape of the shroud is to permit freedom of axial movement of the shroud without freezing or binding on the convolutions 18 of the bellows. Of course, the amount of taper on the shroud may be changed so as to suit requirements.

The benefits that are received from the spring control are naturally the tightening of the braided shroud G when the bellows F are in a compressed position. As previously pointed out, if the springs 30 were not used,

the braid would belly out affording no protection to the outside of the bellows F; and, of course, in extended position, the springs 30 will tighten up and the braided shroud will be held taut.

The flexible metallic bellows F when made and used with the outer tubular braided metallic shroud G, is primarily for the purpose of permitting them to be used for tiexing applications with pressurized media. In fact, such tubular braided shroud is asolutely essential as the pressures increase to relatively high values in order to prevent the bellows from rupturing.

half of such multiple strands of wire are spirallyV wound in a clockwise direction and the other half counterclockwise, which provides a fairly uniform non-torquing exibility with end restraint. In other words, the shroud G will hold the pipe section B from rotating with respect to the pipe section A, and thus the bellows F will not be twisted around its axis 31.

The tubular braided shroud G functions reasonably well; however, it creates somewhat an engineering paradox. When the pressures reach fairly high values, the tubular braided shroud is elongated to a point where it would cease to stretch without severance. This elongation automatically decreases the tubular cross-sectional area of the shroud, causing it to bind around the circumference of the bellows `F. This severe constricting eect gradually decreases the flexing ability of the bellows; and, when carried to the limits of the tensile strength of the braided strands of wire 34, it will result in shroud rupture or severance, and the shroud is then useless for further service.

Current trend for higher and higher pressures, but with a continuance for the requirements of great flexibility of the bellows` F, has caused considerable concern. Study of this problem has finally brought about the present concept in control of the tubular braided shroud tension. Regardless of the end load pressure and the taking up of all reserve slack in the shroud so that it is taut throughout its entire length and circumference, the larger end 32 of the shroud will be pulled upon by the springs 30, and this will still permit maximum exing of the assembly regardless of the fact as to whether or not it may be under full pressure load.

The spring-controlled shroud would have physical dimensions and metallurgy compatible with service requirements. Furthermore, the spring loading might be with either single or multiple series of coil springs, with a spring tension compatible with the pressure requirements of the design parameter. Naturally, the metallurgy of such springs 30 `would also conform to the design parameter.

This unique and very functional spring-loaded braided Shroud G not only will maintain a uniform tension on the tubular braid and permit it to be flexed its full range of deliection; but, also, it will automatically eliminate any torsional stresses on the shroud. It has the advantage of increasing the servieeability range of the tubular braided shroud many times, and simultaneously it will reduce the stress and strain on the shroud, thereby greatly increasing its service life.

The spring-loaded floating shroud G is fully automatic in that it automatically will adjust itself to the pressure load conditions. It will adjust itself automatically to the deflection requirements and to any pressure variations or pressure cycling conditions. Likewise, there will be automatic adjustment for thermal expansion and contraction.

Moreover, the provision of the springs 39 will greatly increase the life of the tubular braided shroud G, because there is a material reduction in the spiralling cross-abrasion of the strands of wire 34. Such abrasion is very severe in a normal tubular braid with fixed ends, due to the fact that half of the braid wires are in a clockwise spiral and the other half in a counterclockwise spiral. Without the automatic spring tensioning as provided herein, such cross-abrasion can be and is very severe.

This tubular braided shroud G is also automatic in that it requires absolutely no services attention. There is nothing to adjust, clean, lubricate or anything about it which would require attention in the field. It is factory installed and good for the service life of the exible metallic bellows F on which the shroud is installed.

The tubular shroud automatic tension regulator, provided by the flange D, bolts 27 and springs 30, regulates the tension on the shroud G to maintain it uniform around the entire circumference of the shroud, regardless of which way the dexible metallic bellows F with its tubular shroud is dedected or exed. This automatic regulation functions whether the flex is static or being flexed through constant or variable flexing cycles. Also, it provides considerable structural stability and integrity to the entire flexible metallic bellows assembly, regardless of the imposed variables.

This automatic spring-controlled shroud G provides a unique functional performance that is very simple. It has appreciable advantages in the eld of mechanical motion requirements as hereinbefore mentioned.

I claim:

l. In a bellows-type expansion compensator with spring-controlled tubular braided shroud: a pair of spaced pipe sections adapted to be disposed in substantial axial alignment with one another; a tubular metallic bellows interposed between the pipe sections and having opposite ends, one end of the bellows being secured to each of the pipe sections; the pipe sections having bores communicating with an interior passageway of the bellows, whereby a fluid under various pressures and temperatures may be conveyed through the pipe sections and bellows; the bellows dening convolutions that will be compressed, when the pipe sections are moved toward one another in an axial direction, while the convolutions will be expanded as these pipe sections are moved away from one another; a tubular braided shroud telescoped over the bellows and having opposite ends; means anchoring one end of the shroud to one of the pipe sections; the other end of the shroud being free and movable toward and away from the other pipe section, when the bellows is compressed and expanded, respectively, the braided shroud permitting slight angular movement in the bellows during its expansion or contraction; and spring means connected to the free end of the shroud and being operable to maintain the shroud taut, as the bellows is contracted and expanded; the shroud being disposed adjacent to the bellows to provide an exterior support for the bellows; and the tension placed on the shroud being sufficient to prevent the bellows from bulging to one side or the other of its centerline to any appreciable extent when the bellows is compressed.

2. The bellows-type expansion compensator with spring-controlled tubular braided shroud. as set forth in claim 1; and in which the end of the shroud that is anchored to one of the pipe sections contacting with the exterior of the bellows at this end; and the shroud having its other end section spaced outwardly beyond the bellows in all radial directions so as to permit freedom of axial movement as well as slight angular movement of the shroud without binding on the adjacent convolutions of the bellows.

3. The bellows-type expansion compensator with spring-controlled tubular braided shroud, as set forth in claim 1; and in which the spring means are designed to regulate the tension on the shroud to maintain it uniform around the entire circumference of the shroud, regardless of which way the bellows and its shroud is deflected angularly in a lateral direction as well as in a longitudinal direction.

4. The bellows-type expansion compensator with spring-controlled tubular braided shroud, as set forth in claim l; and in which the shroud is frusto-conical in shape; the smaller end of the cone of the shroud being anchored to one of the pipe sections and contacting with the exterior of the bellows at this end; the larger end of the cone of the shroud being spaced outwardly beyond the bellows in all radial directions so as to permit freedom of axial and lateral movement of the shroud without binding on the adjacent convolutions of the bellows; and the spring means being attached to the larger end of the cone of the shroud.

5. lIn a bellows-type expansion compensator with spring-controlled tubular braided shroud: a pair of spaced pipe sections adapted to be disposed in axial alignment with one another; one of the pipe sections being fixed, and the other being disposed for lloating movements both axially and radially; a pair of intermediate flanges, one being secured to each of the pipe sections; a tubular metallic bellows interposed between the pipe sections and having opposite ends, each end of the bellows being secured to one of the intermediate flanges; the pipe sections having bores communicating with an interior passageway of the bellows, whereby a fluid under various pressures and temperatures may be conveyed through the pipe sections and bellows; the bellows dening convolutions that will be compressed, when the pipe sections are moved toward one another in an axial direction, while the convolutions will be expanded as these pipe sections are moved away from one another; a frusto-conical shaped tubular braided shroud telescoped over the bellows; the shroud having a smaller end and a larger end; the smaller and larger ends of the shroud being disposed adjacent to the floating and xed pipe sections, respectively; means anchoring the smaller end of the shroud to the intermediate flange on the oating pipe section; a plurality of bolts ixed to the larger end of the shroud and being disposed around the circumference of the shroud; these bolts sliding freely through openings fashioned in the intermediate ange of the xed pipe section; springs disposed to yieldingly pull on the bolts to maintain the shroud taut, as the bellows is contracted and expanded; the shroud being disposed adjacent to the bollows to provide an exterior support for the bellows; and the tension placed on the shroud being sulicient to prevent the bellows from bulging unduly to one side or the other of its centerline when the bellows is compressed; the shroud permitting a slight angular movement of the bellows in a transverse direction.

6. The bellows-type expansion compensator with spring-controlled tubular braided shroud, as set forth in claim 5; and in which the smaller end of the cone of the shroud contacts with adjacent convolutions of the bellows; the larger end of the shroud being spaced radially in all directions from the adjacent convolutions of the bellows, whereby the larger end of the shroud will move fast and freely under tension of the springs without binding on the convolutions adjacent to the fixed pipe, and will permit slight angular movement of the bellows in a transverse direction.

References Cited in the file of this patent UNITED STATES PATENTS 1,625,684 Roddy Apr. 19, 1927 2,014,355 Hussman Sept. 10, 1935 2,216,468 Farrar Oct. 1, 1940 2,444,988 Guarnaschelli July 13, 1948 FOREIGN PATENTS 87,694 Sweden Oct. 20, 1936 667,144 Germany Nov. 5, 1938 

